How butterflies keep their cool: Physical and ecological traits influence thermoregulatory ability and population trends.

Andrew J Bladon,Adam Mcveigh,Sam J Buckton,Eleanor K Bladon,Tom M Fayle,Richard Knock,Gwen E Hitchcock,Jonah M Walker,Steven R Ewing,Rosa Menéndez,Matthew P Hayes,Colin Lucas,Matthew Lewis,Edgar C Turner,Stuart Corbett,Elise Zipkin

doi:10.1111/1365-2656.13319

Abstract

Understanding which factors influence the ability of individuals to respond to changing temperatures is fundamental to species conservation under climate change. We investigated how a community of butterflies responded to fine-scale changes in air temperature, and whether species-specific responses were predicted by ecological or morphological traits. Using data collected across a UK reserve network, we investigated the ability of 29 butterfly species to buffer thoracic temperature against changes in air temperature. First, we tested whether differences were attributable to taxonomic family, morphology or habitat association. We then investigated the relative importance of two buffering mechanisms: behavioural thermoregulation versus fine-scale microclimate selection. Finally, we tested whether species' responses to changing temperatures predicted their population trends from a UK-wide dataset. We found significant interspecific variation in buffering ability, which varied between families and increased with wing length. We also found interspecific differences in the relative importance of the two buffering mechanisms, with species relying on microclimate selection suffering larger population declines over the last 40years than those that could alter their temperature behaviourally. Our results highlight the importance of understanding how different species respond to fine-scale temperature variation, and the value of taking microclimate into account in conservation management to ensure favourable conditions are maintained for temperature-sensitive species.

Highlights

Climate change affects the distribution, abundance and phenology of species
In 2018, for butterflies perching on vegetation at the time of capture, a third temperature reading was taken by holding the thermocouple a centimetre above the perch location (Tperch), providing a measure of the thermal properties of the butterfly’s chosen microhabitat
While the majority of species were sampled over much of this range some, such as those which only fly in early spring (Dingy Skipper Erynnis tages: 10.0–26.3°C; Duke of Burgundy Hamearis lucina: 13.0–24.7°C; Orange-tip Anthocharis cardamines: 13.1–22.3°C) and one montane specialist (Mountain Ringlet Erebia epiphron: 13.9–26.1°C), were only recorded at a lower range of air temperatures (Fig. 1)

Summary

Introduction

Climate change affects the distribution, abundance and phenology of species. These changes can comprise range shifts, with increases in abundance in the cooler parts of species’ ranges and declines in abundance in warmer parts (Fox et al, 2015; Lehikoinen et al, 2013; Parmesan et al, 1999), and altered activity patterns, with species emerging or becoming active earlier in the year or in warmer conditions (Sparks & Yates, 1997; Thackeray et al, 2010). Changing temperatures can have a marked effect on butterflies, with species at the edge of their distribution showing the most dramatic shifts For a handful of cold-adapted northern or montane species, climate change will likely result in declines (Franco et al, 2006) Given these effects, many habitats are predicted to experience turnover of species and altered species richness as time goes on (González-Megías, Menéndez, Roy, Brereton, & Thomas, 2008; Menéndez et al, 2007). Higher temperatures can change butterfly activity patterns and facilitate more frequent, longer or more effective territorial and mate-locating behaviours, potentially increasing breeding success

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Results

Conclusion